JPH0381073A - Welding machine pressurizing mechanism - Google Patents

Abstract

PURPOSE:To reduce variance of pressuring force of an electrode, to miniaturize the mechanism and to improve the welding quality by bringing the electrode close to materials to be welded and moving it toward the materials to be welded while being decelerated by being regulated by a cam from the midst. CONSTITUTION:When an air cylinder 14 is driven and a cam follower 13 is pushed down a lever 9 falls and a detention member 7 falls integrally. In the process of this fall, the cam follower is abuts on the upper surface of the cam 15. A motor 19 is driven and rotation is transmitted to the cam 15 and further, transmitted to the cam follower 13 which is rotated. The cam follower 13 falls by following lowering of the top face height in accordance with rotation of the eccentric cam 15. The lever 9 further falls and the moment an electrode 1 comes into contact with the materials 20 to be welded, a compression spring 8 contracts and a detection plate 12 comes into contact with a limit switch 11. A specified current is applied to the electrode 1 from a power unit with an output signal of this switch 11 as a starting signal to complete welding.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a technology related to a moving mechanism of a welding head of a welding machine,
In particular, the present invention relates to a technique that is effective when used to optimally move an electrode to a welding point on an object to be welded.

[Conventional technology]

For example, a welding machine for welding small electronic components automatically moves the small electronic component to be welded, presses the welding head to the welding position of the small electronic component set in a fixed position, and performs welding. A structure is in place to do so.

A technique for driving a pressure mechanism of such a welding machine is described in, for example, Japanese Patent Laid-Open No. 180383/1983.

By the way, the present inventor has studied various problems caused by the characteristics of the drive source of the pressurizing mechanism.

The following are the techniques studied by the present inventor, and the outline thereof is as follows.

That is, the drive section of the pressurizing mechanism is configured to operate a vertically moving shaft fixed to the power supply board using a lever, and an air cylinder or a treadle with a wire is usually used to drive this lever.

[Problem to be solved by the invention]

However, in the welding machine pressurizing mechanism that uses an air cylinder as the driving source for the pressurizing means as described above, fluctuations in the air pressure relative to the air cylinder cause variations in the pressurizing speed, or the acceleration due to the cylinder characteristics The inventor has found that there are problems that affect welding quality, such as the energizing force being varied due to positional deviation or speed variations when the electrode and the welding object contact each other, because the movement reaches the maximum speed at the time of contact. Served.

Therefore, an object of the present invention is to provide a technique that allows smooth driving while keeping the pressurization speed constant.

The above objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, in a welding machine that performs welding by moving and bringing an electrode into contact with a workpiece, an air cylinder is used to move the electrode toward the workpiece at the beginning of the movement of the electrode, and an air cylinder is used to move the electrode toward the workpiece during the movement of the electrode. The device is equipped with a cam that restricts movement of the electrode.

[Operation] According to the above-mentioned means, when welding starts, the air cylinder approaches the electrode toward the workpiece via the holding member, and the electrode is regulated by the cam from the middle and is decelerated toward the workpiece. and move. Therefore, the movement of the electrode is initially fast, and then decelerated from the point where it is regulated by the cam in the middle, and the value of the pressing force is kept constant from the time the activation signal is received until the electrode is energized. Make it. Also,
Fluctuations in the pressing force due to the chuck ring can also be reduced.

〔Example〕

FIG. 1 is a side sectional view showing an embodiment of a welding machine pressurizing mechanism according to the present invention.

An electrode 1 that presses into contact with a welding point of a workpiece is held by a power supply plate 2, and a table 3 is disposed on the opposite surface of the electrode 1. The power supply plate 2 is fixed to the lower end of a vertically movable shaft 4 arranged to be movable in the vertical direction. The vertical motion shaft 4 is supported by a bearing 5, and the bearing 5 is supported by a welding machine main body 6.
Fixed. A U-shaped locking member 7 is fixed to the side surface of the midsection of the vertical movement shaft 4, and a compression spring 8 is disposed on the upper surface of the locking member 7.

Further, the locking member 7 is provided with alternating U-shaped levers 9 facing each other, and the upper end of the compression spring 8 is in contact with the lower surface of the upper piece of the lever 9. The locking member 7 is pushed down by this compression and the biasing force of the spring 8, and the vertical movement shaft 4 is pushed down together with this. An energization pressure adjustment screw 10 is disposed above the compression spring 8, and the biasing force of the compression spring 8 can be sub-adjusted depending on the direction of rotation.

A limit switch 11 is attached to the lower surface of the lever 9, and a detection plate 12 is provided at the tip of the lower piece of the locking member 7. When the vertical movement shaft 4 rises to the set position, the detection plate 12 is activated. It comes into contact with the operating piece of the limit switch 11, turns on the limit switch 11, and detects that the vertical movement shaft 4 is at the upper end.

A cam follower 13 is attached to the upper part of the body of the lever 9, and an air cylinder 14 is connected to the cam follower 13. A cam 15 is rotatably disposed opposite the cam follower 13, and a pulley 16 is attached coaxially with the cam 15. The cam 15 has a cycloidal cam curve. Next, pulley 1
A pulley 17 is disposed opposite to the pulley 6, and its rotation axis serves as the rotation axis of a motor 19. Pulley 17 and pulley 1
A timing belt 18 for transmitting the rotational force of a motor 19 is passed between the two.

Next, the operation of the embodiment using the above IT will be explained.

When the workpiece 20 to be welded is set on the table 3 (set so that the distance between it and the lower end of the electrode 1 is a specified value) and a welding command is issued, the air cylinder 14 is driven and the cam follower 13 is pressed down. Ru.

The lever 9 begins to descend together with the cam follower 13, and the locking member 7, which is pressed down and locked onto the lever 9 by the compression spring 8, lowers together. During this lowering process, the cam follower 13 comes into pressure contact with the upper surface of the cam 15.

Next, the motor 19 is driven, and its rotation is caused by the rotation of the motor 19.
, cam 1 via timing belt 18 and pulley 16
5 to the cam follower 13 via the cam 15.
The cam follower 13 rotates. The cam follower 13 descends as the top surface height decreases as the eccentric cam 15 rotates. Under this situation, the lever 9 further descends, and at the same time the electrode 1 contacts the workpiece 20, the compression spring 8 contracts, and the detection plate 12 contacts the limit switch 11. Using the output signal of the limit switch 11 as a starting signal, a predetermined current is applied to the electrode 1 from a power supply device (not shown), and welding is completed.

FIG. 2 shows the displacement/pressure car time characteristics according to the present invention,
FIG. 3 shows the conventional displacement/pressure car time characteristics.

Furthermore, FIG. 4 is a characteristic diagram showing the pressure car time characteristics when the electrode 1 is in contact with the workpiece 20. In the figure, A indicates the conventional energization time, and B indicates the energization time according to the present invention. It shows.

As shown in Figure 3, in the conventional pressurizing method using only cylinders, the speed changes due to fluctuations in the pressurizing force, and as a result, there is a lag in the time until the starting signal pressurizing force is reached.
The applied force is always constant.

However, since there is a delay time t from when the activation signal is received until the current actually flows through the electrodes, the pressing force that fluctuates during that time is different. Therefore, welding conditions change.

On the other hand, in the present invention using a cylinder and a cam, as shown in FIG. 2, since the drive during pressurization is performed by the cam 15,
The pressing force actually applied to the electrode 1 is constant. Therefore, welding conditions are constant and stable.

In addition, when contacting the workpiece, with conventional pressurization using only a cylinder, the electrode contacts the workpiece while accelerating.
As shown by the broken line in FIG. 4, a large chuck ring occurred and the welding conditions changed because current was applied at point A during the occurrence. On the other hand, in the present invention, as shown in the characteristic shown by the solid line, the air cylinder f4 is driven until just before contacting the workpiece 20, and thereafter contact and pressure are performed while being decelerated by the cam 15, so that chatter is eliminated. The welding conditions become constant and stable because the pressure is applied at point B when this chattering has decreased.

Above, the invention made by the present inventor has been specifically explained based on Examples, but it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. stomach.

[Effects of the Invention] Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly explained below.

That is, in a welding machine that performs welding by moving and bringing an electrode into contact with a workpiece, an air cylinder is used to move the electrode toward the workpiece at the beginning of the movement of the electrode, and an air cylinder is used to move the electrode toward the workpiece during the movement of the electrode. Since a cam for regulating the movement of the electrode is provided, variations in the pressing force of the electrode can be reduced, the mechanism can be made smaller, and the welding quality can be improved.

[Brief explanation of drawings]

'JJ1 is a side sectional view showing an embodiment of the welding machine pressurizing mechanism according to the present invention, Fig. 2 is a displacement/pressure car time characteristic diagram according to the present invention, and Fig. 3 is a conventional displacement/pressure car time characteristic diagram. FIG. 4 is a pressure curve time characteristic diagram when the workpiece and electrode are in contact with each other. 1... Electrode, 2... Power supply plate, 3... Table, 4
... Vertical movement shaft, 5... Bearing, 6... Welding machine main body, 7... Locking member, 8... Compression spring, 9...
Lever 10... Energization pressure adjustment screw, 11... Limit switch, 12... Detection plate, 13... Cam follower, 14... Air cylinder, 15... Cam, 16
．． 17...Pulley, 18...Timing belt, 1
9...Motor, 20...Welded object. Funeral 1 Figure 1: Electrode 4: Vertical axis 7: Locking member 8: Compression spring 9 lever 16: Cam follower 14: Air cylinder 15: Cam 19: Motor 20: Welded object

Claims (1)

[Claims] 1. In a welding machine that performs welding by moving and contacting an electrode with respect to a workpiece, an air cylinder that moves the electrode toward the workpiece at the beginning of the movement of the electrode, and an air cylinder that moves the electrode toward the workpiece during the movement of the electrode. A welding machine pressurizing mechanism characterized by comprising a cam that restricts movement of an electrode.